Hello guys, I'm new to GSM modules. I've a very little idea of there working. I bought my gsm module from here: http://www.ebay.in/itm/GSM-GPRS-SIM-900A-modem-with-Stub-Antenna-for-PIC-Atmel-Arduino-Raspberry-Pi-/291389483047?_trksid=p2054897.l5673
I'm trying to send sms from the module but it is not working. I found the following code online but it is not working
void setup()
{
Serial1.begin(9600); //Baud rate of the GSM/GPRS Module
Serial1.print("\r");
delay(1000);
Serial1.print("AT+CMGF=1\r");
delay(1000);
Serial1.print("AT+CMGS=\"+91944xxxxxx8\"\r"); //Number to which you want to send the sms
delay(1000);
Serial1.print("Test SMS \r"); //The text of the message to be sent
delay(1000);
Serial1.write(0x1A);
delay(1000);
}
void loop()
{
}
I’m using an arduino due board.
Could you please post a
Could you please post a picture?
Also, are you using a converter to convert the Arduino voltage levels to RS232?
A MAX232 chip is an old chip, but I remember using one. They probably still make cables to convert from TTL to RS232.
I"m not using any voltage
I"m not using any voltage converter. what converter should i use?
An RS232 to TTL serial cable
According to the ebay posting, the module uses a standard called RS232. This is a serial communications standard that uses 12 volts for communicating. You cannot directly connect the module with your Due without causing major problems. You ay have burned out the Due.
You can make a voltage converter with a MAX 232 chip or just buy a cable that communicates between the two voltage levels.
Search on eBay for "max232"
Search on eBay for “max232” and you’ll find a lot of modules. Of course, these change between 12v and 5v.
Well, luckily my board is
Well, luckily my board is not burnt. Thank you for helping me. can you be more specific with the converter thing or provide me some links where I can buy the cable. I can’t find anything related to this online. Thank you
You should have received an
You should have received an email that included schematics. It would be nice if you could oat the ARM and the ATMEL ones.
I used a multimeter to
I used a multimeter to measure the voltage of the tx and rx pin. the voltage on tx pin was around 2.8v and on rx pin was around 3…3v so i don’t think i need any converters
You’ll need to use the
You’ll need to use the serial ports to hook the two modules together. The module you’ve shown have a female serial port, as does the gsm module. You’ll also need a female to female serial adaptor (one with two male ends).
Or else you can find an RS232 adapter that has a male serial port.
I used a multimeter to
I used a multimeter to measure the voltage of the tx and rx pin. the voltage on tx pin was around 2.8v and on rx pin was around 3…3v so i don’t think i need any converters. and while doing that I think i’ve burnt the gsm module 
Please notice that both the
Please notice that both the ARM 3.3v and the ATMEL 5v schematics have a MAX232 chip to convert the voltages.
To get this to work, you would need to get a MAX232 chip and hook the RX/TX of the MAX chip to the TX/RX of the gsm module.
May I ask why you didn’t just get a gsm module that already had a TTL serial hookup? The same company even releases a few different versions with TTL level interfaces.
because i’m an idiot. i
because i’m an idiot. i didn’t researched enough before buying and now I’ve burnt this module so I think i’ll buy a new one with TTL which is going to cost me a fortune
I doubt that the gsm module
I doubt that the gsm module is hurt. The input expected around 12v, so I doubt the Due could even communicate with it.
Do you have a PC with a real serial port rather than just USB? Those are RS232 ports.
You’re not necessarily an
You’re not necessarily an idiot. You seem mainly inexperienced. I made my share of foolish purchases back in the day.
I contacted the manufacturer
I contacted the manufacturer and visited their lab yesterday. They gave me few codes to test and helped me with interfacing and let me tell you the module works completely fine with arduino board. the tx and rx pins works on 3 to 4 volts the problem is solved. Thank you guys 
hello Dangerousthing could help me on codes i need to receive data using RS-232 , Arduino and Lora i am new begginer on arduino, once i have codes i will do visualization after.
Thanks
Benson
